We shall attempt to elucidate the components which make up the basement membrane produced by cultured bovine corneal endothelial cell cultures. The types of collagen, proteoglycans, glycosaminoglycans, and glycoproteins present in the basement membrane will be analyzed and changes in basement membrane produced by cells maintained in the absence of FGF versus cultures maintained in its presence will be analyzed. The basement membrane produced by cultured bovine corneal endothelial cells will be used to grow human corneal endothelial cells. Since this cell type does not produce a basement membrane when maintained in vitro, it is likely that the growth rate of these cells will be greatly enhanced if they are provided with a basement membrane synthesized de novo. The control of proliferation and differentiation of the epithelial cells of the cornea by the basement membrane produced by the corneal endothelium will be analyzed, as will its effect on the reciprocal synthesis by epithelial cells of a basement membrane. The regeneration "in vivo" of the epithelial layer and its replacement of the epithelium deriving from the cunjunctiva, as well as the mitogenic regulation and acceleration of these processes by EGF will be studied. We shall also study the alteration of the basement membrane in vivo, which can affect the repair of the epithelium, and how the use of EGF can improve it.